1
Do Cellular Telephones Cause Cancer?
Reviewing the Fundamental Issues
Matthew C. Baker, Student, Calvin College Engineering Department

Abstract—In recent years, concern has arisen about
possible health risks associated with the use of cellular
phones. Some recent studies have been published which
suggest that exposure to radio frequency (RF) radiation
(the driving force behind cell phones) may increase the
incidence of cancer in mice, and this has contributed to
the alarm. The goal of this paper is to inform readers
about the physics and technology behind cell phones as
well as to provide an overview of the existing RF
radiation studies as they pertain to cancer. A handful of
pertinent studies are reviewed and the epidemiological
evidence of a link between cancer and RF radiation is
examined and evaluated for its integrity. The findings
presented in this article ultimately suggest that the
evidence for a causal relationship between cell phone
radiation and cancer is relatively weak.
Index
Terms—cancer,
cellular
telephones,
epidemiological studies, RF radiation, specific
absorption rate.
I. INTRODUCTION
S
car drivers (including the author of this paper) feel
unsafe knowing that many of the other drivers on the
road are driving while their hands and minds are occupied
with cell phone conversations. In light of recent scientific
findings, car accidents may not be the only thing that cell
phone users have to fear. Both scientists and laypersons
have recently expressed concern that cellular phone users
may be exposing themselves to radiation that could have
negative health effects. The alarm is not unreasonable. The
widespread use of cellular phones means that each day
millions of people repeatedly place radio frequency (RF)
transmitters against their heads. In 1994, there were 16
million cell phone users in the United States alone. As of
July 17, 2001, there were more than 118 million[1]. A
Scarborough report released in 2003 states that 66 percent of
the U.S. population uses cellular phones, a statistic that
would put current U.S. cell phone use at around 190 million
people[2]. The percentage of users in European and Asian
countries is even higher than in the United States. It is clear
that the sheer size of the cell phone user population itself
warrants a good examination into the safety of this form of
radiant energy.
Anxiety about the possibility of cell phones’ negative
health effects first came to widespread public attention in
OME
Matthew Baker is a senior Electrical Engineering student at
Calvin College in Grand Rapids, Michigan, MI 49546 USA (email: mbaker08@calvin.edu).
Fig. 1. Cell-phone use has been increasing rapidly, which is one
reason why scientists and lawmakers are so concerned about the
potential risks associated with these devices.
1992 in a U.S. court. A Florida resident by the name of
David Reynard filed a lawsuit which claimed that his wife’s
fatal brain cancer had been caused by RF radiation from her
cell phone. A federal court dismissed the suit in 1995 due to
a lack of valid scientific and medical evidence; however, the
issue gained the attention of the public. Several similar
lawsuits and allegations in the media about the dangers of
cell phones and their cancer-causing capabilities have
developed since 1993, and this has spurred an increase in
interest in the biology, physics, and epidemiology of RF
radiation.
The goal of this paper is to provide an overview of the
science behind cellular phones as well as a discussion of the
dosimetry of RF radiation, exposure standards, typical
exposure levels, and possible mechanisms for biological
effects. This is followed by a review of the epidemiological
and experimental studies available on RF radiation, which
includes an evaluation of the current evidence that suggests a
link between cell phone radiation and cancer.
II. THE PHYSICS BEHIND RF RADIATION
A. RF Radiation Basics
Electromagnetic radiation is made up of waves of electric
and magnetic energy moving at the speed of light. All
electromagnetic energy falls somewhere on the
electromagnetic spectrum, which extends from direct current
up to X-rays and gamma rays.
Fig. 2 shows the
electromagnetic spectrum and displays the location of
different types of electromagnetic radiation along its length.
Two types of electromagnetic radiation have been identified:
ionizing and non-ionizing.
Ionizing radiation is
2
Fig. 2. Cell phones fall between microwave ovens and TV transmitters on the electromagnetic spectrum.
that which contains sufficient electromagnetic energy to strip
atoms and molecules from body tissue and alter chemical
reactions in the body[1]. Ionizing waves, such as gamma
rays and x-rays, fall on the rightmost end of the
electromagnetic spectrum and are known to cause damage.
This is why lead vests are placed over patients bodies when
X-ray images are taken. One the other end of the spectrum
is non-ionizing radiation.
Non-ionizing radiation is
generally safe. It has been found to have some heating
effects on tissues, however this is usually not enough to
cause long-term damage[1]. RF radiation, visible light, and
microwaves are all examples of non-ionizing radiation.
Scientists divide the spectrum further into subregions
according to the state of the technology being used and the
characteristics that a specific form of radiation demonstrates.
Cellular and personal communications systems (PCS) are
commonly placed in the “wave” realm. The wave realm
consists of the ultra high frequency (UHF) radiation region,
which spans from 300 to 3000 MHz[3]. Maxwell’s
equations are valid in this region and they are commonly
used for mathematical analysis of the waves herein.
B.
where S/N is the signal-to-noise ratio. Therefore, channel
capacity can be increased by increasing the system’s signalto-noise ratio.
The Shannon theorem establishes the upper limit to the
transfer of information within a channel, however, it does
not describe how this upper limit can be achieved. At
present, channel capacity is increased in wired
communication by adding optical fibers in parellel, with
each fiber optically isolated from its neighbors[3]. In
wireless communications, channel capacity is increased by
transmitting weak signals which attenuate rapidly near the
transmitter. These signals then provide a given portion of
the electromagnetic spectrum to be resued frequently in the
same region by geographically separated and isolated
“cells”[1]. This is the brilliance of the cellular system and it
is why the name “cell” phone has become widely used. This
division of a metropolitan area into cells allows widespread
Channel Capacity and Modulation
A continuous wave of UHF radiation is not useful by
itself. In order for it to become useful, a wave must have
information placed on it through a process called
modulation. Modulation alters the original wave (called the
carrrier) at a rate slightly slower than its nominal frequency
in one of three ways. The two most common modulation
techniques are amplitude modulation (AM) and phase
modulation (FM). These two techniques function just like
their names describe—by varying the amplitude or by
varying the phase of the carrier wave. A third method for
modulation is called digital modulation, which imposes
information on a wave through pulsing.
Each section of the spectrum has a limited capacity for
carrying information. This capacity is described by the
Shannon theorem. According to the Shannon theorem, the
limiting capacity, C (in bits/s), of a communication channel
of bandwidth W (in Hz) is
S

C  W  log 2  1   ,
N

(1)
Fig. 3. Because cell phones and base stations use low power
transmitters, the same frequencies can be reused in adjacent cells.
In this drawing, the two darker cells can reuse the same
frequencies.
frequency reuse across a city so that millions of people can
use cell phones simultaneously (see Fig. 3).
The way a given section of spectrum is allocated among
users affects the channel capacity. Each cell phone carrier
typically receives 832 frequencies to use in a city[1]. Cell
phones use two frequencies per call (a duplex channel) so
that there are normally 395 voice channels per carrier. The
42 other frequencies are used for control channels. Because
of the relatively low signal strength that cell phones possess,
the same frequencies can be “re-used” extensively across the
3
city. The degree of reuse depends in some measure on how
the information is encoded. Because of this, several coding
techniques have been developed; the most common of which
are Frequency division multiple access (FDMA), Time
division multiple access (TDMA), and Code division
multiple access (CDMA).
C. The Dosimetry of RF Radiation
In a basic sense, the power density (in W/m2) across a
surface is given by the relationship
power density  Re (n  S)  Re[n  (E  H*)] ,
(2)
J. E. Moulder brings the possible negative effects of
external exposure into perspective in Cell Phones and
Cancer when he writes, “suppose the power density is ~1
W/m2. If this influx is absorbed, entirely and uniformly, in a
tissue layer 1000 x 1000 x 1 mm, it corresponds to an SAR
of ~1 W/kg. Further, at 1000 MHz, it corresponds to ~1
photon/s deposited in each 1 x 1 x 1-nm cube of tissue”[3].
In the laboratory, SAR can be estimated in a number of
ways. If the effective conductivity is known, micro-antennas
can be used to establish the local electric field in tissue using
(4). Miniature thermal probes can measure the heating of
surrounding tissue and can be used to deduce SAR using the
equation
where Re is the real part of the expression in brackets, S is
the complex (frequency domain) Poynting vector in W/m, n
is a unit vector perpendicular to the surface in question, E is
the complex electric field strength in V/m, and H* is the
complex conjugate of the complex magnetic field strength in
A/m[3]. This equation gives the strength of an incident EM
wave, which is the definition of power density. Power
density is the favored measurement of external exposure to a
UHF field because it is fairly easy to measure. The
ANSI/IEEE c95.1 recommendations for average external
exposure to UHF is
power density (in W/m 2 ) 
SAR  c p
T
t
,
(5)
f (in Hz)
 2 to 20 W/m 2
8
(3)
1.5  10
 0.2 to 2.0 mW/cm 2 .
A recent recommendation from the International
Commission on Non-Ionizing Radiation Protection
(ICNIRP) recommends similar power-density guidelines for
limiting the general public’s exposure to RF radiation. The
purpose of these restrictions is to prevent humans from
becoming overheated by limiting exposures to levels that are
relatively weak. To get a feel for the units of power density,
consider that summer sunshine peaks at around 1000 W/m2.
Despite the friendliness of its units, the measurement of
external exposure that the power density equation provides
has proven to be an inadequate gauge of the significant
conditions within an irradiated organism. Scientists choose
to use a metric of internal exposure called the specific
absorption rate, or SAR (in W/kg). The SAR is the metric
that is typically used to measure doses of RF exposure in
laboratory experiments. The SAR is given by
σ
SAR  (Elocal)  eff
ρ
2
(4)
where Elocal is the r.m.s. electric field (in V/m) in the
organism at the point of interest, σeff is the effective
conductivity in S/m, and ρ is the local mass density in
kg/m3[3]. ANSI/IEEE limits the spatial-average SAR in
uncontrolled environments to 0.08 W/kg for a whole-body,
and to 1.6 W/kg as averaged over any 1 g of tissue. It is
allowable to average power density and SAR over 30-minute
intervals. The ICNIRP restrictions for SAR are comparable
to these ANSI/IEEE limits.
Fig. 4. Power absorbed in the head of a cell phone user.
Computer image created by EM software.
Taken from
www.rfsafe.com.
where cp is the specific heat at constant pressure in J/(kg *
K), and δT is the change in tissue temperature over a time
δt[3]. A more realistic approach involves the use of
numerical models of macroscopic bodies. With an organism
and a well-characterized irradiation geometry, finite
difference time domain (FDTD) simulations can predict
SAR accurately. This method is well-developed and avoids
the difficulties of determining SAR experimentally, as in the
methods above. (See Fig. 5 for an example of this form of
modeling). However, FDTD modeling is expensive and
time consuming.
D.
Human Exposure
In its 1991 update, the IEEE/ANSI guideline for local
SAR limit was set to 1.6 W/kg, averaged over any gram of
tissue[4]. The FCC later adopted this limit and appplied it to
all mobile phones and other small transmitters. The ICNIRP
restriction is currently 2-4 W/kg, which is comparable to the
IEEE/ANSI value. These values were chosen because they
closely resemble the human whole-body resting metabolic
rate and are about 12.5% of the brain’s resting metabolic
rate. Many cell phones operate near the FCC limit, and
require careful measurements in order to establish
compliance.
In the United States, cellular phones operate at low power
levels, but the antenna, which has a time-averaged power
output of about 600 mW for an analog phone and 125 mW
for a digital unit, is placed very near to the head, which can
4
Fig. 5. A example 3D FDTD simulation of dipole radiation.
push exposure levels close to the regulatory limits[4]. The
numerically modeled brain SARs of a cellular phone user
sometimes even exceed the 1.6 W/Kg limit, however, they
usually fall within the “controlled environment” limit of 8
W/kg averaged over six minutes. The exposure levels vary
greatly depending on the precise location of the handset
against the head and on the precise shape and electrical traits
of the user’s head. All of these are quantities that vary for
each person, which makes exposure a complicated
measurement to generalize.
E.
Biological Effects of RF Radiation
An electromagnetic wave can cause a biological change in
living tissue in two ways: depositing enough energy while
passing through the tissue to alter some structures, or by
depositing packets of energy in the tissue that are larger than
the bond energy[5]. For a biological change to occur by way
of altering structure, the EM wave must transfer energy
significantly above kT, where k (1.38 x 10-23 J/K) is the
Boltzmann constant and T is the absolute temperature (in
kelvin, K). At human body temperature (37 degrees C or
310 K), kT is equal to 4.3 X 10 -21 J. To cause a change in
chemical bonds, the EM wave must be capable of depositing
energy packets that are larger than the bond energy, which is
near the value of an electron volt, or 1.6 X 10 -19 J [3].
To put this all into perspective, recall that photons were
discussed earlier in the description of power density. It was
said that if a power density of 1 W/m2 were absorbed into
tissue, at 1000 MHz it would correspond to 1 photon/s being
deposited in each 1 x 1 x 1-nm cube of tissue. The energy
contained in an EM photon is hf, where h (6.625 X 10-34 J s1
) is the Planck constant and f is the frequency of the wave in
Hz (cycles/s). Therefore, in the range 300 to 3000 MHz,
which is the UHF region, the energy of a single photon is
less than 0.1% of kT or the bond energy[3]. Many scientists
argue that due the fact that photon energy is much less than
kT or the bond energy in the UHF realm, there is not much
possibility that UHF radiation could cause biological change
at subthermal power levels.
III. INVESTIGATING A LINK
It is tremendously difficult to prove a link between any
environmental exposure and cancer. This difficulty stems
from the fact that there is no sole cause for cancer, and
because there is no adequate method for continuously
supervising individual exposures or for approximating an
individual’s exposures in the past. The case of RF radiation
is the same. According to oncologychannel.com, the annual
incidence of brain cancer in the United States is 15-20 cases
per 100,000 people[6]. Given the hundreds of millions of
cell phone users in the United States, thousands of these
users will develop brain cancer each year, regardless if there
is a link between RF radiation and cancer at all. Because of
this difficulty, proving or disproving the existence of a link
requires very carefully designed studies.
Health agencies rely on two types of studies when
investigating
possible
cancer-causing
agents:
epidemiological studies and experimental studies with
animals. Epidemiological studies are those that include
statistical analyses of health records in order to establish a
positive or negative correlation between incidence of disease
and exposure. These studies are the type that will be
examined first.
IV. EPIDEMIOLOGICAL STUDIES
The following section of this paper will describe four
recent epidemiologic investigations on cancer risk among
cellular telephone users. The results of each study will be
explained and an evaluation of the study as a whole will be
provided.
A.
USA – Rothman et al. (1996)
The first follow-up study to the David Reynard lawsuit
occurred in 1996. This study was performed by an
epidemiologist by the name of Kenneth Rothman at
Epidemiology Research Institute in Newton Lower Falls,
Massachusetts. This was a cohort study (an observational
study in which a defined group of people (the cohort) is
followed over time and outcomes are compared in subsets of
the cohort who were exposed or not exposed, or exposed at
different levels, to a certain factor of interest) of mortality
among cellular telephone subscribers residing in
metropolitan areas. The four metropolitan areas were
Boston, Chicago, Dallas, and Washington DC.
The
members of the sample group were single phone,
noncorporate customers who had active cellular accounts as
of January 1, 1994. 255,868 subscribers were selected to
investigate the link between mortality and cellular phone
use. 23% of the sample used a nonhandheld (where the
antenna is mounted on a vehicle) phone, while 19% used a
handheld phone (where the antenna is placed close to the
head). The type of phone was unkown for 58% of subjects.
A total of 408 deaths were reported. The overall
mortality rate was lower for handheld cellular telephone
users than for nonhandheld users[7] and mortality rates for
both types of users were far lower than corresponding rates
for the general population. Unfortunately, these results are
inconclusive regarding a link between cancer and cellular
telephone use because total mortality is a non-specific
outcome. The total number of deaths due to cancer was
unknown. Also, the low mortality rate compared with the
general population indicates that a healthy sample was
selected. Nonetheless, this study paved the way for future
epidemiological studies investigating the link, and it
indicated that cell phone users were not in any more danger
than non-cell phone users.
5
B. Sweden – Hardell et al. (1999, 2000, 2001)
Lennart Hardell and his colleagues at the Orebro Medical
Centre in Orebro, Sweden, performed a prevalence casecontrol study (a study that excludes those who died and
cannot provide information about casualty) of persons
between the ages of 20 and 80 who were diagnosed with a
brain tumor between 1994 and 1996 in Sweden. The study
evaluated the mobile phone habits of 209 of these brain
tumor patients and compared these to 425 healthy control
subjects[7].
Questions were asked regarding average
minutes of phone use per day, years of phone use, digital or
analog phone use, type of phone, side of head that phone
was placed on, among other things.
The results of the study showed that there was no
difference in the percentage of cell phone users between the
control group and the test group. There was also no
noteworthy difference in the median number of hours of
telephone use or for the use of analog phones versus digital
phones.
The study revealed one finding that was
informative: users of mobile phones who had developed
certain types of brain tumors were more likely to report
having used the phone on the side of the head with the tumor
than on the other side[4]. The study did not show an
increased risk for brain tumors occurring on the opposite
side of the head than where the phone was positioned.
However, this association was weak. It was not statistically
significant and could be explained as recall bias by the
subjects due to the fact that all of Hardell’s subjects knew
that they had brain cancer before they were questioned.
Also, because there was no overall association between
cellular phone use and brain tumors, it is not reasonable to
conclude that that although cellular phone use does not
cause cancer, it might have the ability to change the location
of the tumor in the brain[7].
Overall, this study did not show an increased risk of brain
tumors associated with cell phone use. The study did show
an increased risk of tumors in certain regions of the brain
associated with cellular phone use on the same side of the
head. However, this risk was balanced by decreased risk in
other regions of the brain associated with this same-side use.
Once again, the association was not statistically significant
due to the small number of test subjects.
C. USA – Muscat et al. (2000)
A study of brain cancer patients in five hospitals in New
York, Massachusetts, and Rhode Island was conducted over
the years of 1994 to 1998. The 469 test subjects were
between the ages of 18 and 80 and had been diagnosed with
primary brain cancer. These test subjects were compared
with 422 other hospital control patients who did not have
brain cancer. The test employed a face-to-face questionnaire
that inquired about handheld cell phone use as well as hours
of use per month and years of use.
14% of the cancer patients reported handheld cellular
phone use and 18% of the control group reported the same.
Mean length of phone use for both groups was 2.7 and 2.8
years, respectively.
Analysis of the existence of an
association was performed using the criteria of years of use,
number of hours used per month, total hours of use, location
of brain cancer, and type of tumor. No significant
associations were found[7]. Brain tumors were more
prevalent on the same side of the head that the telephone was
normally held, however, tumors on the temporal lobe (the
part of the brain that receives the most RF exposure during
cellular phone use) were less prevalent on the same side.
This is the opposite of Hardell’s findings[7].
This study was strong due to its large sample size, the
structured questionnaire that was administered face-to-face,
and the high response rate. The weaknesses of this study
Fig. 6. Age Standardized annual incidence (cases per 100,000) of
ocular malignant melanoma in Denmark 1943-96 and number of
cellular phone subscribers. No increasing trend in the incidence of
melanoma has been observed.
include the fact that only a small number of subjects (5%)
reported longer than four years of cell phone use, and there
is the possibility of recall bias. Recall bias was most likely
lessened because the questionnaire was given to patients
shortly after cancer diagnosis, meaning that the patients’
memory was probably more accurate. Overall, the results of
this study do not suggest an association with an increased
risk of tumors in the areas of the brain that receive the
heaviest RF radiation exposure, which suggests that cellular
phone use does not cause cancer.
D. Germany – Stang et al. (2001); Johansen et al. (2002)
Two incidence case-control studies were carried out in
Germany on occupational risk factors for eight rare forms of
cancer, including uveal melanoma (melanoma of the eye).
The eye is one of the body tissues that is exposed to RF
radiation during cellular phone use. The results were pooled
together to produce a total of 118 cases of uveal melanoma
and 475 matched control subjects. The subjects were asked,
“Did you use radio sets, mobile phones, or similar devices at
your workplace for at least several hours per day[7]?”
Based on the evaluation of the responses that followed,
one of the authors reported a significant four-fold increased
risk of malignant melanoma of the eye for “probable or
certain exposure to mobile phones,” which was based on 12
of the cancer subjects who had reported being exposed.
This study as a whole, however, was mostly inconclusive
relative to cellular phone use due to the fact that it was not
designed to look directly at exposure to cellular phone
radiation[7].
Evaluation of exposure only included
occupational cell phone use, and the responses to the
question regarding “radio sets, mobile phones, or similar
devices” made it difficult to isolate cellular phone exposure.
Other researchers proposed that if the results of this
German study were true, and cellular phone use increases the
6
risk of uveal melanoma by a factor of four, then the
incidence of uveal melanoma should increase over time as
the number of cellular phone subscribers increases. In order
to test this proposition, the incidence rates of melanoma of
the eye between the years 1943 and 1996 were compared
with the number of mobile phone subscribers in Denmark.
There was no increasing trend in the incidence of melanoma
of the eye, even though the number of cellular phone users
grew exponentially over the years in question. See Fig. 6.
studies had shown that excess DNA breaks were not present
after in vitro exposure of cells to RF radiation.
Due to the unique positive findings of these studies, future
studies were needed in order to validate the genotoxic
potential of RF radiation. Two of these follow-up studies
(which employed animal testing) will be described in the
following paragraphs.
E.
This study chronically exposed cancer-prone mice to 2450
MHz RF radiation in order to evaluate cytogenetic damage
in blood and bone marrow cells. Two hundred female mice
were randomly divided into two groups. The first group was
exposed to 2450 MHz RF radiation at an SAR of 1.0 W/kg
20 hours a day, 7 days a week, for 18 months. The second
group of mice was sham-exposed. 75 supplementary mice
were kept as sentinel subjects and examined periodically for
health status. Seven of these sentinels that endured the 18month study were used as positive control animals and were
injected with 1 mg/kg of mitomycin C, which is a DNA
inhibiting anticancer agent. These seven were sacrificed 24
hours after the injection.
Blood and bone marrow smears were made from all of the
mice that survived the 18-month period in order to
determine the incidence of micronuclei. This was performed
by examining 2000 polychromatic erythrocytes in peripheral
blood and in the bone marrow[3]. After the 18-months had
elapsed, there were 62 RF-exposed mice and 58 shamexposed mice remaining. The mean number of micronuclei
per 1000 polychromatic erythrocytes in the exposed mice
was 4.5 in peripheral blood and 6.1 in bone marrow (See
Table I). The mean number for sham-exposed mice was 4.0
in peripheral blood and 5.7 in bone marrow[3]. This
difference proved to be statistically significant for peripheral
blood and bone marrow.
Summary of Epidemiological Findings
The preceding sections described four recent studies that
investigated a link between RF radiation exposure and
cancer. None of the studies that were referenced suggested a
positive correlation between cellular telephone use and
cancer. All other epidemiology studies have also been
mostly or completely negative, and are certainly inconsistent
with any large increase in risk (a doubling or more) of brain
cancer as a result of cell phone use[4]. There are
shortcomings associated with these existing studies. All
studies completed thus far have not concluded anything
about small cancer risks associated with RF radiation; nor
have they said anything about future risks. To shed light on
this aspect, any credible study would need to examine a
person’s cell phone use over a decade or more, which has
been difficult to do given the speed at which cell phone
technology changes[4].
V. ANIMAL EXPOSURE STUDIES
As explained earlier, researchers generally accept that RF
radiation from cellular phones does not contain sufficient
energy to cause biological changes in tissue or break
chemical bonds. Many also argue on physical grounds that
the low energies produced by these non-ionizing radiation
are not capable of causing cancer. Despite the fact that the
majority of genotixicity studies of RF radiation have not
shown significant positive results for harmful potential,
some studies have reported positive effects. The most
notable of these positive reports were by Maes et al. and Lai
and Singh[3], whose studies will be briefly summarized now.
Maes et al. exposed human lymphocytes (white blood
cells that have surface proteins specific for antigens) in vitro
to 2450 MHz RF fields for 30-120 minutes at an SAR of 75
W/kg and reported a significant increase in chromosomal
aberrations[3]. It is difficult to interpret the data produced
by this study because there are uncertainties regarding the
dosimetry of the radiation and the temperature
measurements. There is question as to whether the metallic
temperature probe that was used may have been heated by
the RF radiation and, in turn, caused heat damage to the cells
that the needle touched. Uncertainty also exists in the SAR
measurements that were taken due to the fact that they were
performed during a separate experiment[3].
Lae and Singh exposed rats to 2450 MHz RF radiation at
SARs of 0.6 or 1.2 W/kg for two-hour periods, after which
time they observed breaks in the DNA strands in the rats’
brain cells. These DNA breaks were observed immediately
upon exposure and sometimes after four-hour intervals. This
finding conflicts with existing knowledge about DNA repair
after exposure to other forms of radiation. Also, previous
A.
Vijayalaxmi et al.
Table I. Results of Vijayalaxmi et al. study
The biological significance of this difference should be
examined before any hasty conclusions are made. These
results show that the increase in frequency of micronuclei in
the RF-exposed mice compared to the sham-exposed mice
was only 1 extra micronucleus in every 2000 cells. This is a
7
very small change in biological terms[3]. Also, this change
was observed in animals that were exposed to a large amount
of RF radiation over a long interval. This does not provide
ample evidence to conclude that exposure to RF radiation
causes mutation. In addition, the study did not show that
rats which developed an increased frequency of micronuclei
even developed cancer.
B.
Malyapa et al.
The studies by Malyapa et al. were designed to replicate
and expand the work done by Lai and Singh. Remember
that Lai and Singh reported that RF radiation exposure in
animals could cause breaks in DNA strands in brain cells.
One of the studies by Malyapa et al. was designed in vitro,
which makes it possible to monitor and control cell growth,
temperature, dosimetry and other experimental conditions.
Damage to DNA was measured using an alkaline comet
assay[3]. A comet assay is a rapid and very sensitive
fluorescent microscopic method for examining DNA damage
and repair at the individual cell level.
Cells were exposed in vitro to 2450 MHz continuouswave RF radiation, 836 MHz frequency-modulated RF
radiation, or to 848 MHz MHz RF radiation with CDMA
modulation. The 836 MHz frequency-modulated and 848
MHz RF radiation with CDMA modulation were designed to
reproduce the conditions produced by United States cellular
phones. The environment of exposure was 37 degrees C,
and cells were exposed for periods of 2, 4, or 24 hours. The
2450 MHz study used SARs of 0.7 and 1.9 W/kg, while the
836 and 848 MHz study utilized an SAR of 0.6 W/kg. An
examination of DNA strand breaks was performed directly
after exposure, with the exception of the 2 hour exposure, in
which case examinations were performed both immediately
and four hours after the cells were exposed. There was no
evidence of DNA damage in cells exposed to RF
radiation[3].
A second study by Malyapa et al. used in vivo exposure
and subjected one group of rats for 2 hours to 2450 MHz RF
radiation at an SAR of 1.2 W/kg. A second group of rats
was sham-exposed. Following exposure, the rats were
immediately killed via guillotine, and then the brains were
dissected. There was no difference between the shamexposed and RF-radiation-exposed groups (see Figure 7).
No evidence of DNA damage was observed in brain cells of
the exposed group. This finding is inconsistent with the
results reported by Lai and Singh, who observed DNA
strand breaks in rat brain cells after the rats were exposed to
RF radiation.
C.
Summary of Experimental Findings
Although there have been positive findings in some
experimental studies, no relationship between RF radiation
and cancer has been consistently shown. In fact, many of the
studies that have shown a positive relationship have never
been reproduced (as shown in the previous paragraphs). In
addition, most studies expose animals to whole-body
radiation rather than the head-only exposure that humans
experience from cell phones. It is important to consider the
weight that should be given, in general, to results that are
attained in rats and mice. It is unclear how such results can
be interpreted in terms of human health, regardless if the
results are positive or negative.
Fig. 7. Malyapa et al. in vivo exposure in rats. Sequential
guillotine euthanasia and dissection 4 hours after the end of a 2
hour exposure. Each bar is for two animals that were shamexposed or exposed or exposed to 2450 MHz RF radiation. The
data shows that there is no difference between the groups.
VI. EVALUATION FROM PUBLIC HEALTH
AGENCIES
Several public health agencies have evaluated the
carcinogenic potential of cellular telephone use based on
epidemiological and experimental evidence like the
examples here. Almost all acknowledge that there is not
enough evidence to establish the existence of any health
risks or cancer risks associated with cell phone use.
In response to claims by the media that certain cellular
phones were exceeding the maximum level for radiation
emissions, the FCC issued a statement in October 1999
stating that its guidelines, “already incorporate a large
margin of safety between allowed levels of exposure and
exposure thresholds that have been identified with known
adverse health effects.” The statement went on to read, “[the
excess levels] are well within that safety margin, and,
therefore, there is no indication of any immediate threat to
human health from these phones.” Further studies into the
safety of RF radiation from mobile phones are currently
being pursued by the FCC[8].
The Center for Devices and Radiological Health (CDRH)
of the U.S. Food and Drug Administration issued a statement
in October of 1999 saying, “the available science does not
allow us to conclude that mobile phones are absolutely safe,
or that they are unsafe. However, the available scientific
evidence does not demonstrate any adverse health effects
associated with the use of mobile phones[8].”
In May 1999 in the United Kingdom, the National
Radiologic Protection Board Advisory Group on Nonionizing Radiation concluded, “…there was no human
evidence of a risk of cancer resulting from exposure to
radiations that arise from mobile phones[8].”
These quotations sum up the feelings of the majority of
the scientific, medical, and governmental bodies toward the
evidence of a link between cellular phone use and cancer—
there is no convincing evidence.
VII. CONCLUSION
Since the David Reynard case in 1992, there has been a
flood of activity in the scientific community to assess the
8
possibility that cellular phone users may be putting
themselves at higher risk for cancer. A number of studies
have been published that investigate the association between
the RF radiation emitted by cellular phones and cancer, and
a handful of the epidemiological and experimental studies
have been examined in this paper. On the whole, these
studies have provided little reason for believing that cellular
phones cause cancer. The long-term effects of cellular
phone use have not been adequately evaluated due to the
young age of the technology, however, there has been no
concrete indication of adverse effects so far. The absence of
ionizing radiation and the low energy levels associated with
cell phones make it improbable that these gadgets are
capable of being carcinogenic. Despite this strong negative
indication, it is important that research into the science of
cell phone radiation be continued so that the safety of this
technology can be further confirmed to the public.
At the same time, it must be understood that no amount of
research can prove that a product is completely safe, and so
the author leaves the concerned cellular phone user with this
advice from the Food and Drug Administration Center for
Devices and Radiological Health:
If there is a risk from these products—and at this point we
do not know that there is—it is probably very small. But if
people are concerned about avoiding even potential risks,
there are simple steps they can take to do so. People who
must conduct extended conversations in their cars every day
could switch to a type of mobile phone that places more
distance between their bodies and the source of the RF,
since the exposure level drops off dramatically with
distance. For example, they could switch to: a mobile
phone in which the antenna is located outside the vehicle, a
hand-held phone with a built-in antenna connected to a
different antenna mounted on the outside of the car or built
into a separate package, or a headset with a remote antenna
to a mobile phone carried at the waist. Again the scientific
data do not demonstrate that mobile phones are harmful.
But if people are concerned about the radiofrequency
energy from these products, taking the simple precautions
outlined above can reduce any possible risk[9].
ACKNOWLEDGMENT
M. C. Baker thanks Dr. Paulo F. Ribeiro for his guidance
throughout the development of this paper.
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Matthew C. Baker is a senior Electrical Engineering student at Calvin
College in Grand Rapids, MI. He plans to graduate with a B.S.E. in
Electrical and Computer Engineering in May 2004. After school, Matt
plans to pursue employment opportunities in the West Michigan and
Chicago, Illinois areas.